Abstract

The Condamine plain is an important agricultural zone, with ~118 thousand hectares of irrigated crops. Groundwater pumped from the shallow alluvial aquifer (40-60 GL/yr) accounts for one third of the irrigation water. Sustainable agriculture future implies, among other issues, a reliable supply of groundwater to the farmers, in terms of quality and quantity. The hydrogeology of the shallow Condamine River Alluvium Aquifer (CRAA) was studied for decades in order to provide a management framework and to determine the 'safe yield', as excessive pumping in the past has led to ongoing decline of the water table, up to ~25m in places. Not withstanding the accumulating data and knowledge, the water balance of the aquifer as well as 'safe yield' estimations are still far from being conclusive and has been substantially revised several times during the last decade. The present report, conducted at the University of Southern Queensland (USQ), collates up-to-date hydrogeological knowledge regarding the CRAA, critically evaluates the accepted hydrogeological conventions, highlights puzzling phenomena and recommends needed work, which can be implemented in a rather expeditious and inexpensive fashion, to overcome the existing knowledge gaps. Refining the hydrogeological knowledge regarding the CCRA is timely, as in the last decade there has been a rapid expansion of the CSG industry in vicinity to the Condamine plain, with the aim to extract methane from the underlying layers. The presumed hydrogeological effects of CSG production upon the shallower CRAA have been delineated but are yet to be adequately quantified. It is our view that the hydrogeological knowledge-gaps should be addressed before predictions of CSG activities effects can be made.